Flexible water and oil resistant composites

ABSTRACT

This invention provides air impermeable liquid-water resistant water-vapor-permeable composites that are highly oleophobic and some of which have enhanced water-vapor-permeable properties. In its broadest aspect, the composites comprise: a layer of a microporous polymer that is water-vapor permeable and which is oleophobic, and which is liquid water-resistant. This layer is in contact with an air-impermeable, liquid water resistant, polymer layer that is permeable to water-vapor molecules. The oleophobic microporous polymer layer confers enhanced oleophobicity. In another aspect, a third layer of a microporous, water vapor permeable polymer can also be present on the other side of the air-impermeable polymer layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application based on U.S. patentapplication Ser. No. 08/876,357 filed Jun. 25, 1997, issued on Jun. 13,2000, as U.S. Pat. No. 6,074,738, which was based on provisionalapplication Ser. No. 60/030,916, filed Nov. 14, 1996.

FIELD OF THE INVENTION

The invention relates to flexible laminate composites which areespecially suited for use for water resistant, but water vapor permeabletextile materials, or apparel made from the materials.

BACKGROUND OF THE INVENTION

Materials for use for rainwear are known which have a layer of expandedmicroporous polytetrafluoroethylene (ePTFE) or porous polypropylene, seefor example, Gore, et al., U.S. Pat. Nos. 4,194,041 or Henn, 4,969,998.Expanded microporous water-repellent polytetrafluoroethylene materialdescribed in Gore, U.S. Pat. No. 3,953,566 is especially well suited forthis purpose. It is liquid water repelling, but allows water vapor, inthe form of perspiration, to pass through. Polyurethanes and otherpolymers have been used for this purpose also. To confer goodflexibility on the materials for use in the textile sector, themicroporous layer should be made as thin as possible. However, a thinnermembrane will generally mean a loss of performance, and thin coatingsrun the risk of decreasing water repellency.

U.S. Pat. No. 4,194,041 describes the use of an additional coating onmicroporous polymers which is based on a thin, air-impermeable coatingcomposed of a polyetherpolyurethane or polyperfluorosulfonic acid thattransports water vapor molecules by diffusion. The thin coating isemployed to reduce transmission of surface active agents andcontaminating substances through the polymers. Owing to the chemicalstructure of the polymer, this monolithic coating on the microporousstructure exhibits a high transport of water molecules, (highpermeability to water vapor) through the polymeric material. This filmshould be applied as thinly as possible in order not to affect theflexibility, yet confer adequate protection on the composite.Furthermore, water vapor permeability deteriorates greatly in the caseof thicker, monolithic films.

Other coatings for microporous materials are described in the art. Forexample, EP 0581168 (Mitsubishi) describes the use of fluorinated alkylmethacrylate and fluorinated alkyl acrylate for polyolefin membranes.The substances are physically bound to the polymer matrix and contain acrosslinking monomer. The substance is applied in the form of a solutionusually in fluorinated solvents. After coating, the solvent is removed.The situation is similar with a process for treating polymers withsolutions of amorphous fluoropolymers (WO 92/10532).

Solutions of fluorine-containing polymers are also involved in a patentfor coating ePTFE with Teflon AF (EP 0561875). WO 91/01791 (GelmanSciences Technology; EP 0561277 (Millipore)/U.S. Pat. No. 5,217,802propose treating a porous membrane with a fluorine-containing monomerand a crosslinker. The treatment is followed by polymerization.Perfluoropolyethers in conjunction with ePTFE for use as water-repellentfinish are mentioned in WO 92/21715.

For improved water repellency performance, oleophobicized andhydrophobicized textile substrates sprayed with fluorocarbon emulsionsare mentioned in EP 0594154.

A type of composite membrane is known from U.S. Pat. No. 4,969,998. Inthis membrane the material of the inner layer has in part penetratedinto the pores of the microporous outer layer. As the material for themicroporous outer layer, microporous expanded polytetrafluoroethylene,is proposed. As for the inner layer a polyether-polythioether isproposed. The latter material up to a certain degree fills the pores ofthe microporous layer, but is consistently tight, amorphous andnonporous. It is reported that this composite has moisture vaportransmission rates which are higher than the moisture vapor transmissionrates of the laminate described first. However, when the composite wasused as a textile laminate for rainwear it was found that under extremeathletic load and the associated heavy formation of perspiration, thelatter cannot always be dissipated to the environment without residue.The liquid perspiration remaining on the inside of the clothingadversely affects the feeling of well-being and comfort of wearing.

SUMMARY OF THE INVENTION

It is a purpose of this invention to provide flexible liquid waterresistant, water vapor permeable composites having improved resistanceto contaminants, especially to oil contaminants. The increasedoleophobicity enhances the usefulness of the composites in garments andin separation applications.

It is another purpose of the invention to provide composites of enhancedmoisture vapor transmission rate.

The composites of the invention are flexible, liquid water resistant,oleophobic, water-vapor permeable composites.

In its simplest and first embodiment, the composite is:

(a) a layer of a microporous polymer that is water-vapor permeable,oleophobic, and which is liquid water-resistant, said layer adhered to

(b) an air-impermeable polymer layer that is water-vapor permeable.

The microporous polymer has voids throughout the internal structurewhich form an interconnected continuous air path from one side toanother.

In one embodiment, the composite of the invention is composed of solelylayers (a) and (b) as defined above.

In another second embodiment, a third layer, layer (c), of a microporouspolymer can be present on the other side of the air-impermeable polymerlayer. Layer (c) is also water vapor permeable. It can be made of thesame polymer as used in layer (a) or it can be a different polymer.Preferably it is the same.

In a preferred aspect the microporous polymer layers are exemplified bya porous, expanded polytetrafluoroethylene (ePTFE) film.

In one instance in this second embodiment, membrane (c) may behydrophobic. In another instance it may also be oleophobic. In anotherinstance it may be made oleophobic. In still another instance it ishydrophilic.

Layer (a) is made oleophobic by treating it with an oleophobic polymer,such as, for example, a polymer that has recurring pendant fluorinatedside chains. A trifluoromethyl group will be at the end of the recurringpendant alkyl-perfluoroalkyl groups which depend from the polymerbackbone. Especially useful are polymers with an acrylate ormethacrylate polymer backbone. In one aspect, the microporous filmconsists of ePTFE which is coated with a material that hasperfluoroalkyl groups CF₃—(CF₂)_(n)—, where n is ≧0, append from thepolymer backbone.

In this latter instance, i.e., when layer (c) is hydrophilic, it hasbeen found that when the composite containing this layer is used in agarment and this layer is innermost, the moisture vapor transmissionrate is unexpectedly greater from the inside to the outside than themoisture vapor transmission rate of one of the other three-layercomposites of the invention. This occurrence, which is surprising, maypossibly be attributed to the fact that the moisture vapor transmissionrate of the middle layer (b) increases in excess proportion when liquidwater is present on the boundary surface. It may be that the microporousinner layer which has hydrophilic properties acts like a type of spongeand absorbs the perspiration which forms and distributes it over largersurface areas so that the individual water molecules on the boundarylayer to the inner diffusion layer pass easily or in higherconcentration into solution and thus migrate or diffuse more quickly tothe outer side.

Microporous layer (c) can be rendered hydrophilic using known processes,for example using the process as is described in U.S. Pat. No.5,209,850. Processes for rendering microporous polymers hydrophilic aredescribed in two U.S. Pat. Nos. 5,352,511 and 5,354,587. DE-A 4243955 isalso concerned with rendering initially water-repellent layers offluoropolymers hydrophilic. Other treatment procedures are describedbelow.

DETAILED DESCRIPTION OF THE INVENTION Definitions

By “flexible” is meant easily bent, i.e., pliable.

By “liquid water resistant” is meant that the material is waterproof ata water pressure of 13.8 kN/m².

By “oleophobic” is meant a material has an oil resistance of 1 or more.

By “microporous” is meant a material has very small, microscopic voidsthroughout the internal structure which forms an interconnectedcontinuous air path from one surface to the other.

By “air-impermeable” is meant that no airflow is observed for at leasttwo minutes as determined by the Gurley test described below.

By “water vapor permeable” is meant an MVTR or at least 1000 g/m² per 24hr, preferably 2000 g/m² per 24 hr.

By “hydrophilic” material is meant a porous material whose pores becomefilled with liquid water when subjected to liquid water without theapplication of pressure.

By “adhered” is meant layer to layer surface contact or impregnation,fully or partially, of layer (b) into the pores of layer (a), as well asadherence by use of an adhesive.

Suitable microporous polymers for layers (a) and (c) herein includefluoropolymers, e.g. polytetrafluoroethylene or polyvinylidenefluorides, polyolefins, e.g. polyethylene or polypropylene; polyamides;polyesters; polysulfone, poly(ethersulfone) and combinations thereof,polycarbonate, polyurethanes. To achieve flexibility, the layers shouldbe thin.

If the microporous polymer of layer (a) is not naturally oleophobic, itcan be rendered oleophobic by treating it with an oleophobic material.Usually application of oleophobic materials to the polymer is byapplying a liquid form of the material, e.g., a melt, or solution orlatex dispersion of the material, as, e.g. by dipping, painting,spraying, roller-coating or brushing the liquid on the surface.Application is carried out until internal surfaces of the microporousstructure are coated, but not until the pores are filled as that woulddestroy or severely lessen the water-vapor transmitting property of thelayer. Thus, the presence of the oleophobic polymer has little effect onthe porosity; that is, the walls defining the voids in the microporouspolymer preferably have only a very thin coating of the oleophobicpolymer. Application of the oleophobic material can be achieved byvarying the concentration, solids content of the solution or dispersion,and/or by varying the application temperature, or pressure.

Common oleophobic compositions are oleophobic fluorocarbon compounds.For example, the fluorocarbon can be one that contains perfluoroalkylgroups CF₃—(CF₂)_(n)—, where n is ≧0. The following compounds or classesof oleophobic materials can be used.

Apolar perfluoropolyethers having CF₃ side groups, such as FomblinY—Ausimont; Krytox—DuPont;

Mixtures of apolar perfluoroethers with polar monofunctionalperfluoropolyethers PFPE (Fomblin and Galden MF grades available fromAusimont);

Polar water-insoluble PFPE such as, for example, Galden MF withphosphate, silane, or amide, end groups;

Mixtures of apolar PFPE with fluorinated alkyl methacrylates andfluorinated alkyl acrylate as monomer or in polymer form.

The above-mentioned compounds can be crosslinked by, for example, UVradiation in aqueous form solution or emulsion.

The following can also be used:

Microemulsions based on PFPE (see EP 0615779, Fomblin Fe20microemulsions);

Emulsions based on copolymers of siloxanes andperfluoroalkyl-substituted (meth)acrylates (Hoechst);

Emulsions based on perfluorinated or partially fluorinated co- orterpolymers, one component containing at least hexafluoropropene orperfluoroalkyl vinyl ether;

Emulsions based on perfluoroalkyl-substituted poly(meth)acrylates andcopolymers (products of Asahi Glass, Hoechst, DuPont and others).

Microemulsions based on perfluoroalkyl-substituted poly(meth)acrylatesand copolymers (WU, U.S. Pat. Nos. 5,539,072; 5,460,872);

Complexes of polyelectrolytes and long-chain perfluorinated surfactants(see U.S. Pat. No. 4,228,975), compounds which can be used according tothat reference with preference are: PFPE—COOH (perfluoropolyether withterminal carboxyl groups), perfluorocarboxylic acids, CF₃—(CF₂)_(n)—COOHn>6.

Perfluoroalkylsulfonic acids, e.g. CF3—(CF₂)_(n)—SO₂OH n>6.

In one embodiment the coating comprises a solvent-free system of PFPE ora combination of various PFPEs.

It Is well known that —(CF₂)_(n)—CF₃ pendant groups impart very lowsurface energy values to the polymer and thus impart good oil and waterresistance properties. Representative such oleophobic polymers can bemade from organic monomers having pendant perfluoroalkyl groups. Theseinclude fluoroalkyl acrylates and fluoroalkyl methacrylates havingterminal perfluoroalkyl groups of the formula:

wherein n is a cardinal number of 1-21, m is a cardinal number of 1-10,and R is H or CH₃ ⁻; fluoroalkyl aryl urethanes, for example

fluoroalkyl urethane acrylates; fluoroalkyl acrylamides; fluoroalkylsulfonamide acrylates and the like.

It is understood that in the perfluorinated alkyl end groupCF₃(CF₂)_(n), it is difficult to prepare a compound in which n is asingle numeral and that the end group is commonly a mixture of groupshaving varying chain lengths in which n is a mixture of predominantly 5,7, 9.

These polymers and their preparation are known in the art.

In a preferred aspect, these oleophobic polymers are delivered from anaqueous latex in which the diameter of the polymer particles are in thenanoparticle range, 0.01 to 0.5 micrometer. Such particles prepared frommicroemulsions are described e.g., in Wu, U.S. Pat. Nos. 5,539,072 andWu, 5,460,872.

The air-impermeable polymer layer (b) is water-vapor permeable andtransports individual water molecules across its molecular structure.This phenomenon is well known. But because of its nature, the bulktransport of liquids and gases is inhibited. The layer is very thin andserves as support and barrier layer. The (b) layer can be for examplepolyurethane, or a copolyether, copolyester or a silicone. In thesepolymers, especially polyurethanes, passage of water vapor molecules isfacilitated by presence of repeating oxyethylene units:

—(CH₂—CH₂—O—)

in the polymer chain. Polyurethanes of this nature are described inHenn, U.S. Pat. No. 4,532,316 as well as Gore, U.S. Pat. Nos. 4,194,041and 4,942,214. The amount of the ethylene oxide units can vary greatly,e.g., from over 70% to as little as 10%. Copolyethers andcopolyetheresters, such as those described in U.S. Pat. Nos. 4,725,481and 4,493,870 are also useful. Also useful are polyethyleneimines,polyoxyethyleneamines, polyoxypropylene amines, and polyvinylamines,polyacrylics. Also useful are closed cell foams of such polymers.

The air-impermeable polymer layer (b) is combined with the oleophobicpolymer layer (a) by any one of several methods. The air-impermeablepolymer can be applied in liquid form from a liquid mixture or can beapplied in solid sheet form. If the polymer is in sheet form, it can belaminated to the oleophobic membrane by passing the sheets through niprolls or using a breathable adhesive. Alternatively, the microporouspolymer material and the air-impermeable polymer can be combined beforethe oleophobic material is applied. In this variation, the microporouspolymer layer can be treated by brushing or coating by any otherconventional means, including spraying or roll coating or the like. Aconvenient polymer for layer (b) is a water-vapor permeableair-impermeable polyurethane, such as Hypol® 2000. It can be appliedpre-crosslinked or can be crosslinked after application.

Materials that can be used to treat the microporous polymers to makethem hydrophilic to make them useful as layer (c) include: aqueous,alcoholic or aqueous/alcoholic solutions of a copolymer oftetrafluoroethylene and vinylacetate, polyacrylic acid and copolymersthereof, polyacrylamide and copolymers thereof, polyvinyl acetate (PVA),polystyrenesulfonate; polyethylene-, or propylene glycols (PEG, PPG),hydrophilic silicones; anionic, cationic, nonionic or amphoteric surfaceactive agents or mixtures, and complexes of the above. Treatment withhydrophilic material is accomplished by the same technique describedabove for treatment with oleophobic materials.

The methods of preparation of the three-layer composites, i.e., wherelayer (c) is present, is the same. Microporous layer (c) can bepretreated to render it oleophobic or hydrophilic, as the case may be.This can be done before the layer is affixed or after, as describedabove.

In one method to produce a triple-ply composite, the pre-crosslinkedpolyurethane resin with curing agent is applied to a first film of ePTFEby means of a roll coater. The coating weight can, for example, be 10g/m². Then another microporous ePTFE layer is applied and the layersjoined in this way are routed through a gap between the two pressurerolls so that not yet completely crosslinked resin is pressed to acertain degree into the microporous structure and penetrates into thepores. The polyurethane resin can however be adhered or laminated as afinished film to one of the layers first, as is described, for example,in DE-PS2925318. Then one layer (layer (a)) of microporous film isrendered oil-repellent. The other layer can then be rendered hydrophilicor oleophobic by treatment described above; or can remain untreated.

The layer thicknesses, densities and pore sizes of the ePTFE layers usedcan vary, depending on the application.

The composites of the invention can be laminated to fabrics on one orboth sides and the resulting material used to make waterproof butwater-vapor permeable garments.

The composite can be used in conjunction with rainwear and athleticclothing. Of course the composite can also be used in other industrialapplications, where it can be used to remove molecules of low molecularweight from solutions, in distillation, sewage concentration,concentration of juices or biological systems or also in dialysisapplications. The prerequisites for this application are the selectivediffusion behavior of the middle layer which must have higher solubilityfor the passing molecules than for the other molecules of the mixture tobe concentrated.

In the embodiment in which layer (c) is hydrophilic, the composite isadvantageous in that presence of pin holes, etc., does not lead toleaks. Water penetrating via a hole on the inside, i.e., the side facingthe body of the wearer, will first form a drop. This drop, however, willagain be transported into this inner layer by capillary forces andtransported to the middle layer (b). On this surface, the water isdistributed over the surface and is “transferred” as vapor from there tothe outside.

TEST PROCEDURES

Air Permeability/lmpermeability—Gurley Number Test

Gurley numbers were obtained as follows:

The resistance of samples to air flow was measured by a Gurleydensometer (ASTM) D726-58) manufactured by W. & L. E. Gurley & Sons. Theresults are reported in terms of Gurley Number which is the time inseconds for 100 cubic centimeters of air to pass through 6.54 cm² of atest sample at a pressure drop of 1.215 kN/m² of water. A material isair-impermeable if no air passage is observed over 120 second interval.

Oil Repellency Test

In these tests, oil rating was measured using the AATCC Test Method118-1983 when testing film composites. The oil rating of a filmcomposite is the lower of the two ratings obtained when testing the twosides of the composite. The higher the number, the better the oilrepellency. A value of greater than 1, preferably 2 or more, morepreferably 4 or more, is preferred.

The test is modified as follows when testing laminates of the filmcomposite with a textile. Three drops of the test oil are placed on thetextile surface. A glass plate is placed directly on top of the oildrops. After 3 minutes, the reverse side of the laminate is inspectedfor a change in appearance indicating penetration or staining by thetest oil. The oil rating of the laminate corresponds to the highestnumber oil that does not wet through the laminate or cause visiblestaining from the reverse side of oil exposure. The higher the number,the better the oil repellency. A value of greater than 1, preferably 2or more, more preferably 4 or more, and most preferably, 6 or more, ispreferred.

Moisture Vapor Transmission Rate Test (MVTR)—Method A

In this procedure, approximately 70 ml of a solution consisting of 35parts by weight of potassium acetate and 15 parts by weight of distilledwater was placed into a 133 ml polypropylene cup, having an insidediameter of 6.5 cm at its mount. An expanded polytetrafluoroethylene(PTFE) film having a minimum MVTR of approximately 60,000 g/m² per 24hours as tested by the method described in U.S. Pat. No. 4,862,730 toCrosby using potassium acetate and available from W. L. Gore &Associates, Inc. of Newark, Del. was heat sealed to the lip of the cupto create a taut, leakproof, microporous barrier containing thesolution. A similar expanded PTFE film was mounted to the surface of awater bath. The water bath assembly was controlled at 23° C., plus orminus 0.2° C., utilizing a temperature controlled roll and a watercirculating bath. The sample to be tested was allowed to condition at atemperature of 23° C. and a relative humidity of 50% prior to performingthe test procedure. Samples were placed so the microporous polymericfilm to be tested was in contact with the expandedpolytetrafluoroethylene film mounted to the surface of the water bathand an equilibration of at least 15 minutes was used for laminates withtextiles and at least 10 minutes for film composites, prior to theintroduction of the cup assembly. The cup assembly was weighed to thenearest {fraction (1/1000)} g and was placed in an inverted manner ontothe center of the test sample. Water transport was provided by thedriving force between the water in the water bath and the saturated saltsolution providing water flux by diffusion in that direction. The samplewas tested for 15 minutes and the cup assembly was then removed andweighed again. The MVTR is calculated from the weight gain of the cupassembly and expressed in gm of water per square meter of sample surfacearea per 24 hours.

Moisture Vapor Transmission Rate Test (MVTR)—Method B

This method is same as Method A except that the sample rests directly onthe water, i.e., there is no PTFE film mounted to the surface of thewater bath.

EXAMPLE 1

An oleophobic expanded microporous polytetrafluoroethylene (PTFE) filmwas prepared by coating an expanded microporous polytetrafluoroethylene(PTFE) film provided by W. L. Gore & Associates, Inc. The film prior tocoating had a nominal pore size of 0.2 micron and a weight of about 23g/m2 and thickness of about 65 micrometer and a Gurley number of 7.5sec.

The film was rendered oleophobic by treating it with an aqueous latex ofan organic polymer having pendant perfluoroalkyl side chains obtainedfrom W. L. Gore & Associates, Inc. prepared based on Example 1B in U.S.Pat. No. 5,539,072 (incorporated herein by reference) such that the oilrating of 8 was measured for the film after coating and subsequentlydrying at 200° C. The Gurley number was 14 sec, indicating that thepores were still open. The now oleophobic film was coated with awater-vapor permeable, Hypol® 2000 (W. R. Grace & Co.) prepolymer withcuring agent of hexamethylene diamine to yield a composite of the firstembodiment of the invention. The composite readily transmitted moisturebut was impermeable to air. The composite was tested for moisture vaportransmission rate and oil repellency: The MVTR was 11,000 g/m² per 24hrs and the oil rating measured on the side of the film away from theair-impermeable polymer layer was 8.

In the Gurley test, no air flow was observed, demonstrating that acompletely air-impermeable polyurethane coating was applied.

The composite was spotwise adhered to a polyester fabric. The filmcomposite was positioned such that the continuous polyurethane layerfaced away from the fabric. An MVTR using Method A of 11,000 g/m² per 24hr was measured for this laminate when the polyurethane layer wastowards the water.

In contrast, the MVTR of a composite of the expanded microporouspolytetrafluoroethylene coated with the Hypol® 2000, but which was nottreated with the aqueous latex of the organic polymer had an oil ratingof zero. The MVTR was 14,230 determined by Method A.

EXAMPLE 2

An oleophobic expanded microporous polytetrafluoroethylene (PTFE) filmwas prepared by coating an expanded microporous polytetrafluoroethylene(PTFE) film provided by W. L. Gore & Associates, Inc. The film prior tocoating had a nominal pore size of 0.2 micron and a weight of about 23g/m2 and thickness of about 65 micrometer and a Gurley number of 7.5sec. The membrane was rendered oleophobic by treating it with an aqueouslatex of an organic polymer having pendant perfluoroalkyl side chainsobtained from W. L. Gore & Associates, Inc. prepared based on Example 1Bin U.S. Pat. No. 5,539,072 such that the oil rating of 8 was measuredfor film after coating and subsequently drying at 200° C. The Gurleynumber was 14 seconds.

Two separate layers of the coated film were then bonded together withthe Hypol® 2000 prepolymer by simultaneously passing the two layersthrough a nip roll with the Hypol® 2000 prepolymer between the layers.Pressure on the nip forced a portion of the Hypol 2000® prepolymer topenetrate both layers of the coated film. The composite structure wasthen allowed to moisture cure. The oleophobic composite structure thusproduced, readily transmits moisture but is impermeable to air. Thecomposite structure when tested for oil repellency had a repellency of 8measured on both sides of the composite structure. No air flow wasobserved using the Gurley test.

The lack of air permeability indicates that a completely air-impermeablepolymer coating was applied. The MVTR of the composite using Method Awas 7,000 g/m² per 24 hr.

EXAMPLE 3

An oleophobic material, Galden MF 201 (Ausimont), a mono and bistrifluoromethyl-poly-oxyperfluoroalkylene-methylenepolyoxyethylene-phosphate of average mol. weight of 850 g/mol, whichcontains phosphate groups, is polar and is of highly viscous to waxyconsistency at room temperature. It was heated to 50-70° C. and appliedby roll coating using a heated roll to one side of an expandedpolytetrafluoroethylene microporous film coated with a water vaporpermeable (breathable) polyurethane prepolymer of MDI and an alkyleneoxide described in U.S. Pat. No. 4,942,214. The Galden coating weight isadjusted via nip settings and roller pressures so that an add-on of1.0±0.2 g/m² is achieved. The Galden coating is applied to the sideopposite the polyurethane coating.

To homogenize and heat-set the coating, the coating step is followed byheating in a continuous oven at 150-170° C. for a residence time of0.5-5 minutes.

The oil rating, determined on the MF201-coated side, is 4. The MVTRusing Method A is 22,000 g/m² per 24 hr. The chemical stability orpermanence is assessed by performing wash tests at 60° C. The compositeis still oleophobic after washing.

EXAMPLE 4

Example 3 was repeated except the coating weight was 2±0.3 g/m² insteadof 1±0.2 g/m². Coating material, thermal treatment and coatingtechnology were unchanged.

The oil rating on the MF201-coated side was 6. The MVTR using Method Awas 20,500 g/m² per 24 hr. The chemical stability or permanence wasdetermined by performing wash tests at 60° C. The composite was stilloleophobic after washing or after dry cleaning with perchloroethylene.

EXAMPLE 5

Coating material, thermal treatment and coating procedure were as inExample 3 except that the coating weight was 5±1 g/m². The oil rating onthe MF201-coated side was 7. The MVTR using Method A was 19,000 g/m² per24 hr. The material retained oleophobicity after washing.

EXAMPLE 6

a) A mixture of an oleophobic apolar polyfluoropholyether (Fomblin VAC 25/6) mol wt 3300 g/mol, Ausimont Spa, Italy) with Galden MF 201 inmixing ratio of 65% MF 201 and 35% of the Fomblin were used. Coating andthermal treatment were as in Example 3. Coating weight was 2±0.2 g/m².Oil value was 4 on the coated side. MVTR was 20,000 g/m² per 24 hr.

b) Part a) was repeated except that the mixing ratio was adjusted to 80%of MF201 and 20% of the Fomblin.

The coating weight was determined by weighing to be 2±0.2 g/m². The oilrating on the side coated with PFPE mixture was 6. The MVTR using MethodA was 19,000 g/m² per 24 hr.

The material retained its oleophobicity after washing.

Fomblin VAC 25/6 is 1-propene, 1,1,2,3,3,3 hexafluoro-oxidized,polymerized, Mw 3300 g/mol.

EXAMPLE 7

A process for the oleophobilization of an ePTFE composite membranecoated with a breathable polyurethane was carried out with the followingtreatment steps:

The porous side (see Example 3) of the material was wetted with 1:2isopropanol/water.

A polyelectrolyte solution (see table below) was applied by rollcoating. This was followed by the application of an aqueous fluorosurfactant solution, squeezing off, drying and heat setting the materialat 150° C.

The results are presented in the table.

Polyelectrolyte Fluoro surfactant (% by Weight) Oil value Polyallylamine(PM) 5% strength FC 99 (3M >2 (0.1N) (Aldrich Chemical Company, Inc. PAA(0.1N) Fe20 AG (Ausimont) >2 Polyethyleneamine 5% strength FC 99 (3M) >2(PEI) (0.1N) G100 G100 (0.1N) Fe20 AG (Ausimont) >2

EXAMPLE 8

The coating material used was a polysiloxane having fluorinated sidechains (Nuva 4190, Hoechst) in a mixing ratio 20% of Nuva/80%isopropanol. Coating technology and thermal treatment were carried outas described in Example 3. The coating weight is 2.5±0.2 g/m². The oilrating on the coated side was 6. The MVTR using Method A was 19,000 g/m²per 24 hr.

EXAMPLE 9

A microemulsion FE 20 AG (Ausimont), which has a low viscosity at roomtemperature, was roll-coated onto the microporous polymer side of acomposite of expanded PTFE and the polyurethane described in Example 3.The coating weight was adjusted via nip settings and roller pressures sothat an add-on of 2.0±0.2 g/m² was achieved.

Fe 20AG is a Fomblin microemulsion in water, density 1.16 g/ml at 25° C.and consists of Galden MF 310 neutralized with ammonia; and Galden MF3100, a trifluoromethyl-polyoxyperfluoroalkylene-methylene carboxylicacid.

To homogenize and heat-set the coating, the coating step was followed bytreating the film in a continuous oven at 150-1700 for a residence timeof the coated material of 5 minutes. The results were an MVTR value of17,500 g/m² per 24 hr using Method A and an oil rating of >2.

EXAMPLE 10

The coating material used was perfluoropolyether Fomblin Y VAC 06/6 (Mw1800 g/mol, Ausimont).

The perfluoropolyether was applied to the microporous film side(substrate similar to Example 3) by guiding the film over a coating rollat a linear speed of 40-60 m/min. To achieve the necessary coatingviscosity, the rolls are heated to 50-70° C. The applied coating issubsequently homogenized in a continuous oven at 130° C. in the courseof a residence time of 12 to 18 sec. The add-on was 3.5±0.5 g/m². Ascanning electron micrograph of the coated microporous structure showsthat only the inner surface of the structure is coated. The water vaporpermeability, expressed as the MVTR using Method A, was 18,500 g/m² per24 hr, The oil rating on the membrane side coated withperfluoropolyethers is 2.

The material produced was used to produce textile composite layers(composites, textile laminates) as 2- and 3-ply laminates by bondingtextile sheet materials composed of polyester or polyamide on one orboth sides to the membrane by spotwise adhesion.

Laminates can also be produced using Fomblin Y VAC 16/6 (Mw 2800 g/mol,Ausimont).

EXAMPLE 11

A composite was prepared by laminating together two expanded microporouspolytetrafluoroethylene (PTFE) films provided by W. L. Gore &Associates, Inc. The two PTFE films had a nominal pore size of 0.25 μm,a weight of about 20 g/m² and a thickness of 40 μm. For lamination awater-vapor-permeable polyurethane resin (PUR) as described in Example 3was applied and partially penetrated into the microporous structure ofthe first film using a roll coating device, then the second film waslaminated using the PUR as the adhesive between two nip rolls. Aftermoisture curing of the PUR at room temperature, the above mentionedlaminated film was coated on one side with Galden MF 201 (Ausimont) asdescribed in Example 3. In the next step, the other side was coated withthe polymer solution described in U.S. Pat. No. 5,209,850 to render themicroporous PTFE hydrophilic (laydown=4 g/m²). After drying, theresulting composite turned clear on one side after immersion in water.

The moisture vapor transmission rate for this composite was measured byMethod B by first facing the oleophobic side, then the hydrophilic sideof the membrane towards the water.

MVTR measured by Method B shows 25,000 g/m² per 24 hr for the sidetreated with Galden MF and 71,000 g/m² 24 hr for the hydrophilic sidefacing the water.

EXAMPLE 12

A composite was prepared as in Example 11 with one side coated withGalden MF 201. This composite was laminated on the Galden treated sideto a 120 g/m² polyester textile using a spot wise adhesion process.After lamination, the untreated side was coated with the polymerdescribed in U.S. Pat. No. 5,209,850 as in Example 11.

MVTR measured with Method B shows 7200 g/m² per 24 hr for textile sidefacing the water and 21,500 g/m² per 24 hr for the hydrophilic film sidefacing the water.

EXAMPLE 13

A composite was prepared as in Example 11, except that for hydrophilictreating, a commercial available antifogging spray (Nigrin Anti FoggingSpray, Inter-Union Technohandel Landau) was applied on one side. MVTRmeasured with Method B shows 27,000 g/m² per 24 hr for the untreated and79,000 g/m² per 24 hr for the hydrophilic side facing the water.

We claim:
 1. A flexible liquid-water-resistant, water-vapor-permeable,composite comprised of: a). a layer of a microporous polymer film thatis water-vapor-permeable, and a microporous structure comprising amicroporous polymer that has a coating on at least a portion of the porewalls of the microporous polymer, of a second material that impartsgreater oleophobicity to the microporous polymer, said layer ofmicroporous polymer film having been treated to render it oleophobic sothat it has an oil rating of at least 2; said layer adhered to b). anair-impermeable polymer that is water-vapor-permeable; and c). a layeradhered to the side of layer b) that is opposite layer a), said layer c)having a water-vapor-permeable microporous structure comprising amicroporous polymer that has a coating on at least a portion of the porewalls of the microporous polymer, of a second material that impartshydrophilicity to the microporous polymer.
 2. The composite of claim 1laminated to a textile on one or both sides.
 3. The composite of claim 1wherein the microporous polymer of parts a) and c) is expandedpolytetrafluoroethylene.
 4. The composite of claim 3 where layer (b) isa polyurethane.
 5. The composite of claim 1 wherein the microporousstructure of part a) is liquid-water-resistant.
 6. A flexibleliquid-water-resistance, water-vapor-permeable, composite comprised of:a). a layer of a microporous polymer film that is water-vapor-permeable,and a microporous structure comprising a microporous polymer that has acoating on at least a portion of the pore walls of the microporouspolymer, of a second material that imparts greater oleophobicity to themicroporous polymer, said layer of microporous polymer film having beentreated to render it oleophobic so that it has an oil rating of at least2; said layer adhered to b). an air-impermeable polymer that iswater-vapor-permeable; and c). a layer ahered to the side of layer b)that is opposite layer a), said layer c) having a water-vapor-permeablemicroporous structure comprising a microporous polymer which ishydrophilic.
 7. The composite of claim 6 laminated to a textile on oneor both sides.
 8. The composite of claim 6 wherein the microporouspolymer of parts a) and c) is expanded polytetrafluoroethylene.
 9. Thecomposite of claim 8 where layer (b) is a polyurethane.
 10. Thecomposite of claim 6 wherein the microporous structure of part a) isliquid-water-resistant.
 11. The composite of claim 6 wherein said layer(c) is selected from polyurethane and polyamide.